201015589 六、發明說明： 【發明所屬之技術領域】 本發明係有關於鋁膏及其在矽太陽能電池生產中的應 用亦即，其在珍太陽此電池的銘背面電極以及該等個別 矽太陽能電池生產中的應用。 【先前技術】 一種具有卩型基材的傳統太陽能電池結構具有一通常位 於該電池的正面或向陽面之負電極及一位於背面之正電 • 極。眾所周知，在一半導體本體之P-n接面上所照射之具 有適^波長的輕射用以作為一外部能源，以在本體中產生 電子電洞對。在p-n接面處所存在的電位差使電洞和電子 朝相反方向越過該接面，藉此造成能向一外部電路傳遞電 力的電流流動。大多數太陽能電池是經過金屬化（亦即， 具有導電金屬接點）的矽晶圓之形式。 在一矽太陽能電池之形成期間，通常在該矽晶圓之背面 ©上網版印刷及乾化鋁膏。然後，在高於鋁熔點的溫度下燒 製該晶圓，以形成一銘-碎溶融物，隨後在冷卻階段期 間’形成一換雜有銘的蟲晶成長石夕層。該層通常被稱為背 面電場（back surface field, BSF)層，並且有助於改善太陽 能電池的能量轉換效率。 目前使用的大多數發電太陽能電池為矽太陽能電池。大 量生產的流程通常致力於最大簡化之達成及製造成本之最 小化。特別是藉由使用像網版印刷之方法由金屬膏來製成 電極。 143174.doc 201015589 下面將配合圖1來描述此生產方法的範例。圖1A顯示一 p 型矽基底10 ^ 在圖1B中’以磷（P)等物質的熱擴散形成一具有相反導 電型態的η型擴散層20。通常使用三氣氧磷（p〇ci3)做為氣 態破擴散源’其他液體源是填酸等物質。在沒有特別修飾 的情況下’該擴散層20形成於該矽基底1〇的整個表面上 方。在p型摻雜的濃度等於η型摻雜的濃度之情況中，形成 該p-n接面；p-η接面靠近向陽面的傳統電池具有介於〇〇5 μιη和0.5 μιη之間的接面深度。 在該擴散層形成後’透過諸如氫氟酸之酸的蚀刻從剩餘 表面移除過量表面玻璃。 接著，透過諸如電漿化學氣相沉積（CVD)之製程以圖1D 所示之方式在該η型擴散層20上形成一具有0 05 μιη至0.1 μηι厚之抗反射塗層（ARC)30。 如圖1E所示’在該抗反射塗層30上方網版印刷及乾化一 用於上電極的正面銀膏（上電極形成用的銀膏）500。此 外’在該基底的背面上接著網版印刷及依序乾化一背面銀 或銀/鋁膏70及一鋁膏60(可使用一些其它施加方法來達 成）。通常’先將該背面銀或銀/銘膏網版印刷至;5夕上，以 成為兩條平行帶（匯流條（busbars))或成為複數長形條 (垂片（tab))’以準備用做焊接互連線條（預焊的銅帶）， 然後’將該銘膏印刷在裸露區域中，並與該背面銀或銀/ 銘膏稍微重疊。在一些情況下’在印刷該鋁膏之後，再印 刷該銀或銀/鋁膏。然後，通常在一帶式爐中燒製i至5分 143174.doc 201015589 鐘的時間，使該晶圓達到一在70〇至9〇〇r範圍内的峰值溫 度。可依序燒製或共燒該上及下電極。 因此，如圖1F所示，在該燒製期間來自該膏的熔融鋁融 化了矽，接著在冷卻時形成了一從該矽基材1〇磊晶成長的 共晶層，從而形成一包含高濃度鋁摻雜的叶層4(^該層通 常被稱為背面電場（BSF)層，並且有助於改善該太陽能電 池的能量轉換效率。一薄鋁層通常存在於該磊晶層的表面 上。 透過燒製，該鋁膏從一乾燥狀態60轉變成為一鋁背面電 極61 ^同時，將該背面銀或銀/鋁膏7〇燒製成一銀或銀/鋁 背面電極71。在燒製期間，該背面鋁和該背面銀或銀/鋁 之間的界面呈現一合金狀態，並且還電性連接。該鋁電極 佔該背面電極的大部分區域，部分歸因於需要形成p+層 40。銀或銀/铭背面電極形成於該背面的數個部分上（通 常為複數條2至6 mm寬的匯流條），以作為一用以透過預焊 的銅帶等來互連太陽能電池之電極。此外，該正面銀膏 5〇〇在燒製時燒結並穿透該抗反射塗層3〇，從而能夠與該打 型層20發生電接觸。此類方法通常稱為「燒穿 trhrough)」。該燒穿狀態在圖if的層5〇1中清晰可見。 上述這樣的鋁膏已揭露於許多專利申請案中，例如，在 US-A-2007/0079868中。在後者中，揭示在該等鋁膏中所 包含的鋁粉可包括霧化鋁。鋁可以在空氣或惰性環境中被 霧化。 由石夕晶圓所製成且具有鋁背面電極的石夕太陽能電池為 143174.doc 201015589 矽/鋁雙金屬帶，並且會呈現一所謂翹曲特性（bowing behavior)。因為翹曲可能會導致該等太陽能電池的斷裂和 碎裂，所以它是不受期望的❶翹曲亦會造成有關矽晶圓處 理的問題。在處理期間，一般利用帶有吸盤的自動抓握裝 置將矽晶圓提起’而在過度翹曲的情況下吸盤可能無法可 靠的工作。光電產業中的翹曲通常要求該等大陽能電池的 撓曲（deflection)小於1.5 mm。特別對於由大片或薄型矽晶 圓（例如’具有小於180 μηι(特別在120 μηι至小於180 μιη間 範圍）厚度及250以上至400 cm2面積之矽晶圓）所製成的矽 太陽能電池而言’翹曲現象之克服是一項挑戰。 【發明内容】 本發明係有關於用於形成矽太陽能電池的p型鋁背面電 極的銘膏（銘厚膜組成物本發明進一步有關於在石夕太陽 能電池生產中該等鋁膏的形成及使用的方法以及該等矽太 陽能電池本身。 本發明係有關於鋁膏’其包括：粒狀鋁、一有機載體， 以及任選的一種或多種玻璃料組成物，其中該粒狀鋁包括 30至90 wt%(重量百分比）的球狀鋁粉和1〇至7〇 wt%的結狀 (不規則狀）鋁粉，wt%是以該球狀鋁粉和該結狀鋁粉的總 和為基礎。 本發明並有關於一種形成一矽太陽能電池的方法以及該 石夕太陽能電池本身’其中該矽太陽能電池利用一具有一 p 型和η型區域及一 p_n接面的矽晶圓，該方法包括施加（特別 是網版印刷）本發明的鋁膏於該矽晶圓之背面上，以及燒 143174.doc 201015589 製該印刷表面，從而該晶圓達到一在7〇〇至9〇〇。〇範圍内的 峰值溫度。 【實施方式】 現已發現到關於以鋁厚膜組成物（包含上述特定重量比 率的球狀鋁粉和結狀鋁粉）所製造的矽太陽能電池的翹曲 和電氣性能，該鋁厚薄膜組成物呈現出良好及相當均衡的 總體特性。在矽太陽能電池的鋁背面電極之生產中使用該 • 等新型鋁厚膜組成物，不僅使該等矽太陽能電池具有低翹 曲特性和良好的電氣性能，而且還可降低或甚至去除該鋁 背面電極與該矽晶圓基底間的黏附損失傾向。該鋁背面電 極與該矽晶圓基底間的良好黏附可以使該等矽太陽能電池 具有延長的耐久性或使用壽命。另一益處在於，使用本發 明的鋁膏所獲得的鋁_矽共晶層和背面電場的厚度非常均 勻。 本發明的鋁膏包括粒狀鋁及一有機載體（有機介質），其 φ 中該粒狀銘包括30至90 Wt%的球狀鋁粉和10至70 Wt%的結 狀銘粉’ wt°/❶是以該球狀鋁粉和該結狀鋁粉的總和為基 礎。在某一實施例中，球狀鋁粉加上結狀鋁粉的總和佔該 粒狀銘的90 wt%以上。在另一實施例中，其總和佔該粒狀 铭的 100 wt%。 該粒狀銘可以由鋁或含一種或多種其他金屬（例如， 鋅、錫、銀或鎂）的鋁合金所構成。在鋁合金之情況中， 紹的含量為例如99.7至小於1 〇〇 wt0/〇。 如先前所述，該粒狀鋁包括30至90 wt%的球狀鋁粉和10 143174.doc 201015589 至70 wt%的結狀鋁粉，wt%是以該球狀鋁粉和該結狀鋁粉 的總和為基礎《在某一實施例中，該粒狀鋁係由30至90 wt%的球狀鋁粉和1〇至70 wt%的結狀鋁粉所組成，其中 wt°/。的總和為1 〇〇 wt%。 在另一實施例中，該粒狀鋁包括50至75 wt%的球狀鋁粉 和25至50 wt%的結狀鋁粉，wt%是以該球狀鋁粉和該結狀 銘粉的總和為基礎。在另一實施例中，該粒狀鋁係由5〇至 75 wt%的球狀鋁粉和25至50 wt%的結狀鋁粉所組成，其中 wt%的總和為1 〇〇 wt〇/〇。 在又另一實施例中，該粒狀鋁包括60至7〇 wt〇/〇的球狀鋁 粉和30至40 wt%的結狀鋁粉，wt%是以該球狀鋁粉和該結 狀鋁粉的總和為基礎。在某一實施例中，該粒狀鋁係由6〇 至70wt%的球狀鋁粉和3〇至4〇^%的結狀鋁粉所組成，其 中wt%的總和為1 00 wt%。 隹此便用術时％队站树」。Έ走指在顯微鏡下所觀筹 到的個別鋁粒子具有像球或近似球的形狀’亦即，它們月 以是完美的圓形或略帶橢圓形。球狀鋁粉通常以液態鋁名 一具有低氧氣含量（例如，少於5至〇體積百分比）的惰性氣 體環境（例如氮氣或氬氣環境）中的霧化所製成。可用 於本發明的銘膏之市場上可買到的的球狀紹粉之範例是201015589 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to an aluminum paste and its use in the production of a solar cell, that is, the front electrode of the battery of the solar cell and the individual silicon solar cells. Production applications. [Prior Art] A conventional solar cell structure having a crucible type substrate has a negative electrode which is usually located on the front or the sunny side of the battery and a positive electrode which is located on the back side. It is known that a light beam having a suitable wavelength that is illuminated on a P-n junction of a semiconductor body acts as an external source of energy to create an electron hole pair in the body. The potential difference present at the p-n junction causes the holes and electrons to pass over the junction in the opposite direction, thereby causing a current flow that can transfer power to an external circuit. Most solar cells are in the form of tantalum wafers that are metallized (ie, have conductive metal contacts). During the formation of a solar cell, usually on the back side of the germanium wafer © online printing and drying aluminum paste. Then, the wafer is fired at a temperature higher than the melting point of aluminum to form an in-situ smelt, and then a stellate growth layer is formed during the cooling phase. This layer is often referred to as a back surface field (BSF) layer and helps to improve the energy conversion efficiency of solar cells. Most of the power generation solar cells currently in use are germanium solar cells. The process of mass production is usually focused on maximizing simplification and minimizing manufacturing costs. In particular, the electrode is made of a metal paste by using a method such as screen printing. 143174.doc 201015589 An example of this production method will be described below in conjunction with FIG. Fig. 1A shows a p-type germanium substrate 10. In Fig. 1B, an n-type diffusion layer 20 having an opposite conductivity type is formed by thermal diffusion of a substance such as phosphorus (P). Phosphorus oxy-phosphorus (p〇ci3) is usually used as a source of gas-breaking diffusion. Other liquid sources are substances such as acid. The diffusion layer 20 is formed over the entire surface of the crucible substrate 1 without special modification. In the case where the concentration of the p-type doping is equal to the concentration of the n-type doping, the pn junction is formed; the conventional battery having a p-n junction close to the sunny side has a junction between 〇〇5 μm and 0.5 μm depth. Excess surface glass is removed from the remaining surface by etching through an acid such as hydrofluoric acid after the diffusion layer is formed. Next, an anti-reflective coating (ARC) 30 having a thickness of 0 5 μm to 0.1 μm is formed on the n-type diffusion layer 20 by a process such as plasma chemical vapor deposition (CVD) in the manner shown in FIG. 1D. As shown in Fig. 1E, a front side silver paste (silver paste for forming an upper electrode) 500 for the upper electrode is screen-printed and dried over the anti-reflection coating layer 30. Further, a backside silver or silver/aluminum paste 70 and an aluminum paste 60 (which may be achieved using some other application methods) are subsequently screen printed on the back side of the substrate and sequentially dried. Usually 'first print the back silver or silver / paste paste to the screen; on the 5th, to become two parallel strips (busbars) or become a plurality of long strips (tabs) to prepare Used as a solder interconnect (pre-welded copper strip), then 'print the paste in the bare area and slightly overlap the back silver or silver/marker. In some cases, the silver or silver/aluminum paste is reprinted after printing the aluminum paste. Then, it is usually fired in a belt furnace for i to 5 minutes 143174.doc 201015589 minutes to bring the wafer to a peak temperature in the range of 70 〇 to 9 〇〇 。. The upper and lower electrodes may be sequentially fired or co-fired. Therefore, as shown in FIG. 1F, the molten aluminum from the paste melts the ruthenium during the firing, and then forms a eutectic layer which is epitaxially grown from the ruthenium substrate 1 冷却 upon cooling, thereby forming a high inclusion layer. Concentration aluminum doped leaf layer 4 (this layer is commonly referred to as the back surface electric field (BSF) layer and contributes to improving the energy conversion efficiency of the solar cell. A thin aluminum layer is usually present on the surface of the epitaxial layer By firing, the aluminum paste is transformed from a dry state 60 to an aluminum back electrode 61. At the same time, the backside silver or silver/aluminum paste 7 is fired to form a silver or silver/aluminum back electrode 71. During firing. The interface between the back aluminum and the back silver or silver/aluminum exhibits an alloy state and is also electrically connected. The aluminum electrode occupies most of the back electrode portion, in part due to the need to form the p+ layer 40. Silver Or a silver/inscription back electrode is formed on several portions of the back surface (usually a plurality of bus bars 2 to 6 mm wide) to interconnect the electrodes of the solar cell through a pre-welded copper tape or the like. In addition, the front silver paste 5〇〇 is sintered and worn during firing The anti-reflective coating 3〇, so that electrical contact can occur with the play-type layer 20. Such methods are commonly referred to as "burn trhrough)." This burn-through state is clearly visible in layer 5〇1 of Fig. Such an aluminum paste as described above is disclosed in a number of patent applications, for example, in US-A-2007/0079868. In the latter, it is revealed that the aluminum powder contained in the aluminum pastes may include atomized aluminum. Aluminum can be atomized in air or in an inert environment. The Shixi solar cell made of Shixi wafer and having an aluminum back electrode is a 143174.doc 201015589 矽/aluminum bimetal strip and exhibits a so-called bowing behavior. Since warpage may cause breakage and chipping of such solar cells, it is an undesired warpage of the crucible which may cause problems with the handling of the wafer. During processing, the wafer is typically lifted using an automatic gripping device with a suction cup, and the suction cup may not work reliably in the event of excessive warpage. Warpage in the photovoltaic industry typically requires that these solar cells have a deflection of less than 1.5 mm. Especially for tantalum solar cells made from large or thin tantalum wafers (eg, 'wafers having a thickness of less than 180 μm (especially in the range of 120 μηη to less than 180 μηη) and from 250 to 400 cm2) 'Overcoming the warping phenomenon is a challenge. SUMMARY OF THE INVENTION The present invention relates to a paste for forming a p-type aluminum back electrode of a tantalum solar cell (Ming thick film composition. The present invention further relates to the formation and use of such aluminum paste in the production of Shi Xi solar cell. Method and the same solar cell itself. The present invention relates to an aluminum paste which comprises: granular aluminum, an organic vehicle, and optionally one or more glass frit compositions, wherein the granular aluminum comprises from 30 to 90 A wt% spherical aluminum powder and a crucible (irregular) aluminum powder of 1 to 7 wt%, based on the sum of the spherical aluminum powder and the crucible aluminum powder. The invention further relates to a method of forming a solar cell and the solar cell itself, wherein the germanium solar cell utilizes a germanium wafer having a p-type and an n-type region and a p_n junction, the method comprising applying (especially screen printing) the aluminum paste of the present invention is formed on the back side of the germanium wafer, and the printed surface is made by burning 143174.doc 201015589, so that the wafer reaches a range of 7 〇〇 to 9 〇〇. Peak temperature [Embodiment] It has been found that the warpage and electrical properties of a tantalum solar cell fabricated by using a thick aluminum film composition (including the above specific weight ratio of spherical aluminum powder and knotted aluminum powder), the aluminum thick film composition The material exhibits a good and fairly balanced overall characteristics. The use of the new aluminum thick film composition in the production of aluminum back electrodes for solar cells not only makes these solar cells have low warpage characteristics and good electrical properties. And also reducing or even removing the tendency of adhesion loss between the aluminum back electrode and the germanium wafer substrate. Good adhesion between the aluminum back electrode and the germanium wafer substrate allows the germanium solar cell to have extended durability Or a service life. Another benefit is that the thickness of the aluminum-germanium eutectic layer and the back surface electric field obtained by using the aluminum paste of the present invention is very uniform. The aluminum paste of the present invention comprises granular aluminum and an organic vehicle (organic medium), The φ of the grain includes 30 to 90 Wt% of spherical aluminum powder and 10 to 70 Wt% of the knot-shaped powder 'wt°/❶ is the spherical aluminum powder and the knotted aluminum powder And in a certain embodiment, the sum of the spherical aluminum powder plus the knotted aluminum powder accounts for more than 90% by weight of the grain. In another embodiment, the sum of the grains accounts for 100% of the grain. The granule may be composed of aluminum or an aluminum alloy containing one or more other metals (for example, zinc, tin, silver or magnesium). In the case of an aluminum alloy, the content is, for example, 99.7 to less than 1. 〇〇wt0/〇. As previously described, the granular aluminum includes 30 to 90 wt% of spherical aluminum powder and 10 143174.doc 201015589 to 70 wt% of agglomerated aluminum powder, and wt% is the spherical aluminum Based on the sum of the powder and the agglomerated aluminum powder, in one embodiment, the granular aluminum is composed of 30 to 90 wt% of spherical aluminum powder and 1 to 70 wt% of crucible aluminum powder. Where wt°/. The sum of these is 1 〇〇 wt%. In another embodiment, the granular aluminum comprises 50 to 75 wt% of spherical aluminum powder and 25 to 50 wt% of crucible aluminum powder, and wt% is the spherical aluminum powder and the knotted powder Based on the sum. In another embodiment, the particulate aluminum is composed of 5 to 75 wt% of spherical aluminum powder and 25 to 50 wt% of crucible aluminum powder, wherein the sum of wt% is 1 〇〇wt〇/ Hey. In still another embodiment, the granular aluminum comprises 60 to 7 〇wt〇/〇 of spherical aluminum powder and 30 to 40% by weight of the agglomerated aluminum powder, and the wt% is the spherical aluminum powder and the knot Based on the sum of the aluminum powders. In one embodiment, the particulate aluminum is composed of 6 至 to 70 wt% of spherical aluminum powder and 3 〇 to 4 〇 of the lumped aluminum powder, wherein the sum of wt% is 100 wt%. This will use the team to keep the team." The individual aluminum particles that are observed under the microscope have a shape like a sphere or an approximate sphere', that is, they are perfectly round or slightly elliptical. Spherical aluminum powder is typically produced by atomization in a liquid aluminum name, an inert gas environment having a low oxygen content (e.g., less than 5 to 〇 volume percent), such as a nitrogen or argon atmosphere. An example of a commercially available spherical powder that can be used in the present invention is
Poudres-Hermillon的產品 ULT-0665。 在此使用術語「結狀銘粉」，它是指在顯微鏡下所觀察 到的個別㈣子不具有球形形狀。它們具有不規則但緊密 的形狀’亦即’具有低的縱橫比㈣―），並且 143 丨 74.doc 201015589 與銘薄片或銘薄板混淆。結狀鋁粉通常以液態鋁在空氣中 的霧化所製成。可用於本發明的鋁膏之市場上可買到的結 狀銘粉之實例是Alcoa的產品1401/S2。 該球狀銘粉和該結狀鋁粉兩者呈現以雷射散射法所測定 之例如4至12 μιη的平均粒度（平均粒徑，d5〇)。該粒狀鋁 以總銘膏組成物為基礎可以以5〇至8〇 wt%之比例存在於本 發明的銘膏中，或者在某一實施例中，以7〇至75 wt〇/。之比 例存在於本發明的鋁膏中。 本說明和申請專利範圍中所有有關平均粒度的陳述係有 關於在該鋁膏組成物中所存在的相關材料的平均粒度。 在該等銘膏中所存在之粒狀鋁可以附帶有其他粒狀金屬 (例如’銀或銀合金粉末此類其他粒狀金屬的比例以粒 狀銘加上粒狀金屬的總量為基礎為例如〇至i 〇 wt〇/〇。 在某一實施例中’本發明的鋁膏還包括用作無機黏合劑 的一種或多種玻璃料。該等玻璃料組成物可以包含pb〇 ; 0 在某一實施例中’該等玻璃料組成物可以不含錯。 該等玻 璃料組成物可以包括在燒製時經歷再結晶或相分離，並釋 放出具有低於初始軟化點之軟化點的分離相之玻璃料的那 些物質。 該等玻璃料組成物的（初始）軟化點（玻璃轉移溫度，在丄〇 K/min的加熱速率下以差熱分析dTA所測定）可以在325至 6〇〇°C的範圍内。 該等玻璃料呈現以雷射散射法所測定之例如2至2〇 的 平均粒度（平均粒徑）。在該等鋁膏包括玻璃料的情況中， 143174.doc 201015589 玻璃料的含量以總鋁膏組成物為基礎可以為〇 〇1至5 wt°/〇 ’或在某一實施例中，為〇1至2 wt%，或在另—實施 例中，為 0.2至 1.25 wt0/〇。 該等銘膏中有用的一些玻璃料在該項技藝中是常見的。 一些範例包括硼矽酸鹽玻璃和矽鋁酸鹽玻璃。範例還包括 氧化物的組合，例如：B2〇3、Si〇2、Al2〇3、Cd〇、Ca〇、 BaO、ZnO、Na20、Li20、PbO、以及 Zr02，它們可以單 獨使用或組合使用，以形成玻璃黏合劑。 傳統的玻璃料可以為硼矽酸鹽玻璃料（例如，硼妙酸 鉛、硼矽酸鉍、硼矽酸鎘、硼矽酸鋇、硼矽酸鈣玻璃料， 或者其他鹼土金屬硼矽酸鹽玻璃料）。此類玻璃料的製備 係眾所周知的，以及例如在於將氧化物形式的玻璃成分熔 融在一起，再將熔化的組成物倒入水令，以形成玻璃料。 當然，該等批料成分可以是在玻璃料生產的一般條件下能 獲得到所需氧化物的任何化合物。例如，用蝴酸製備氧化 硼，用火石製備二氧化矽，用碳酸鋇製備氧化鋇等等。 可以將玻璃置於球磨機中用水或惰性低黏度、低沸點的 有機液體來研磨，以縮小玻璃料的粒度，並得到粒度實質 均句的玻璃料。接著，使其在水中或該有機液體中沉澱， 以分離細粉，並將包含細粉的上層液移除。還可以使用其 他分類方法。 ' 该等玻璃係藉由以所需比例混合該等期望成分及加熱該 混合物來形成熔融物的傳統玻璃製造技術所製備 技藝中所㉟知，加熱至一峰值溫度有—段時間， 。如該項 以便使該 143174.doc 201015589 熔融物完全變成液體並且均勻。 本發明的鋁膏包括一有機載體。 了將各式各種惰性黏稠 材料用作有機載體。該有機載體 β , 飛取體可以是一種使得粒狀成分 (如果有的話，是指粒狀鋁、玻 敬喁科）此夠以足夠的穩定性 分散於其中的有機裁艚。兮古地丑Λ 4± 戟體5亥有機載體的特性(特別是流變 特性)可以對該銘膏組成物提供良好的施加特性，立包 括：不溶固體的穩定分散性、針對施加（特別是針對網版 參 ％刷）的適當黏度和觸變性、石夕晶圓基底和膏固體的適當 潤濕性、良好的乾化速率及良好的燒製特性。本發明的紹 膏中所用的有機載體可以是非水惰性液體。該有機載體可 以是一有機溶劑或一有機溶劑混合物；在某一實施例中， 該有機載體可以是-在有機溶劑中含有機聚合物的溶液。 某實施例中，用於此用途的聚合物可以為乙基纖維 素。其他可單獨使用或組合使用的聚合物的範例包括乙基 羥乙基纖維素、木松香、酚醛樹脂以及低級醇的聚（甲基） Φ 丙烯酸酯。合適的有機溶劑的範例包括醇酯和萜烯（例 如，α-或β·萜品醇或其與他種溶劑例如煤油、鄰苯二甲酸 —0曰、二乙二醇丁醚、二乙二醇丁醚醋酸.酯、己二醇以 及间/弗點醇的混合物）。此外，在該有機載體中還可包括 用以在該紹膏施加於該矽晶圓背面之後促進快速硬化的揮 發性有機溶劑。這些溶劑和其他溶劑可配製成各種組合， 以獲得所需的黏度和揮發性要求。 在本發明的鋁膏中的有機溶劑含量可以以總鋁膏组成物 為基礎在5至25 wt%範圍内，或在某一實施例中，是在1〇 143174.doc 11 201015589 至20 wt。/。範圍内。 該（等）有機聚合物可以以總鋁膏組成物為基礎以在〇至 20 wt%範圍内的比例存在於該有機載體中，或在某—實施 例中，以在5至1〇 wt%範圍内的比例存在於該有機載體 中。 本發明的銘膏可α包括耐熱無機化合物和/或金屬有機 化合物。「耐熱無機化合物」是指能夠耐受燒製過程中的 熱條件的無機化合物。例如，它們具有高於燒製過程中所 經歷之溫度的熔點。範例包括無機氧化物(例如，無定形 二氧化矽）。金屬有機化合物的範例包括錫有機化合物和 鋅有機化合物（例如，新癸酸鋅和2_乙基己酸亞錫 本發明的鋁膏可以包括一種或多種有機添加劑(例如， 表面活性劑、增稠劑、流變改質劑和穩㈣）。該（等）有機 添加劑可是該有機載體的一部分。然而，在製備該等銘膏 時’也可個別添加該（等）有機添加劑。該（等）有機添加劑 可以以總鋁膏組成物為基礎以例如〇至1〇 wt%之總比例存 在於本發明的鋁膏中。 在本發明的㈣中之有機載體含量可以取決於該膏之施 加方法及所使用之有機載體的種類，因此該含量可以是變 動的。以總鋁膏組成物為基礎，在某一實施例中，該含量 可乂疋20至45 wt/0’或在某一實施例令該含量可以是在 22至35 wt%範圍内。2〇至45㈣的數量包括有機溶劑、可 能的有機聚合物和可能的有機添加劑。 本發明的銘膏為黏稠組成物，其可以由該粒狀銘和該 143I74.doc •12· 201015589 (等）任選玻璃料組成物與該有機載體透過機械混合而成。 在某一實施例中，可以使用動力混合製造方法（一種等同 於傳統輾壓的分散技術）；還可使用輾壓或其他混合技 術。 本發明的銘膏可以直接使用或可以藉由例如添加額外的 有機溶劑來進行稀釋；因此，可以減少該鋁膏之所有其他 成分的重量百分比。Poudres-Hermillon's product ULT-0665. The term "junction powder" is used herein to mean that the individual (four) observed under the microscope does not have a spherical shape. They have an irregular but tight shape 'i.e., have a low aspect ratio (four)-), and 143 丨 74.doc 201015589 is confused with the inscription or the thin plate. The agglomerated aluminum powder is usually produced by atomization of liquid aluminum in air. An example of a commercially available knot powder that can be used in the present invention is Alcoa's product 1401/S2. Both the spherical powder and the agglomerated aluminum powder exhibit an average particle size (average particle diameter, d5 〇) of, for example, 4 to 12 μm as measured by a laser scattering method. The granular aluminum may be present in the paste of the present invention in a ratio of 5 Å to 8 Å wt% based on the total paste composition, or in a certain embodiment, 7 〇 to 75 wt 〇 /. The ratio is present in the aluminum paste of the present invention. All statements relating to the average particle size in this description and in the scope of the patent application relate to the average particle size of the relevant materials present in the aluminum paste composition. The granular aluminum present in these pastes may be accompanied by other granular metals (for example, the ratio of other granular metals such as 'silver or silver alloy powder' is based on the total amount of granular metal plus granular metal. For example, 〇 to i 〇wt〇/〇. In one embodiment, the aluminum paste of the present invention further comprises one or more glass frits used as inorganic binders. The glass frit compositions may comprise pb〇; In one embodiment, the frit compositions may be free of errors. The frit compositions may include undergoing recrystallization or phase separation upon firing and releasing a separated phase having a softening point below the initial softening point. Those materials of the glass frit. The (initial) softening point of the frit composition (glass transition temperature, measured by differential thermal analysis dTA at a heating rate of 丄〇K/min) may be 325 to 6 ° ° Within the scope of C. The glass frits exhibit an average particle size (average particle size) of, for example, 2 to 2 Torr as determined by laser scattering. In the case where the aluminum paste includes a glass frit, 143174.doc 201015589 glass frit The content of the total aluminum paste composition is The basis may be from 1 to 5 wt ° / 〇 ' or in one embodiment, from 1 to 2 wt%, or in another embodiment, from 0.2 to 1.25 wt 0 / 〇. Some useful frits are common in the art. Some examples include borosilicate glass and yttrium aluminate glass. Examples also include combinations of oxides such as: B2〇3, Si〇2, Al2〇3 , Cd 〇, Ca 〇, BaO, ZnO, Na 20, Li 20 , PbO, and ZrO 2 , which may be used alone or in combination to form a glass binder. The conventional glass frit may be a borosilicate glass frit (for example, boron) Lead acid, lead borosilicate, cadmium borosilicate, barium borohydride, calcium borosilicate glass frit, or other alkaline earth borosilicate frits. The preparation of such frits is well known, and for example The glass components in the form of oxides are melted together, and the molten composition is poured into a water to form a glass frit. Of course, the batch components can be obtained under the general conditions of glass frit production. Any compound of an oxide, for example, prepared with a citric acid Boron oxide, preparation of cerium oxide with flint, preparation of cerium oxide with cerium carbonate, etc. The glass can be ground in a ball mill with water or an inert low-viscosity, low-boiling organic liquid to reduce the particle size of the glass frit and obtain the particle size. The glass frit of the substance is then uniformly precipitated in water or the organic liquid to separate the fine powder and remove the supernatant containing the fine powder. Other classification methods can also be used. It is known in the art of the conventional glass making technique of mixing the desired components in a desired ratio and heating the mixture to form a melt, heating to a peak temperature for a period of time, such as to make the 143174.doc 201015589 The melt completely becomes liquid and uniform. The aluminum paste of the present invention comprises an organic vehicle. Various inert viscous materials of various types are used as organic carriers. The organic carrier β, the flying body may be an organic cutting which allows the granular component (if any, refers to granular aluminum, B. sylvestris) to be dispersed therein with sufficient stability. Ugly ugly 4± The characteristics of the organic carrier (especially rheological properties) can provide good application characteristics to the composition of the paste, including: stable dispersion of insoluble solids, for application (especially Appropriate viscosity and thixotropy for screen printing, appropriate wettability of Shihwa wafer substrate and paste solids, good drying rate and good firing characteristics. The organic vehicle used in the paste of the present invention may be a non-aqueous inert liquid. The organic vehicle may be an organic solvent or an organic solvent mixture; in one embodiment, the organic vehicle may be a solution containing an organic polymer in an organic solvent. In one embodiment, the polymer used for this purpose may be ethyl cellulose. Other examples of the polymer which can be used singly or in combination include ethyl hydroxyethyl cellulose, wood rosin, phenol resin, and poly(methyl) Φ acrylate of a lower alcohol. Examples of suitable organic solvents include alcohol esters and terpenes (for example, alpha- or beta-terpineol or other solvents such as kerosene, phthalic acid - 0 oxime, diethylene glycol butyl ether, diethyl ethane A mixture of alcohol butyl ether acetate, hexane diol, and meta/Fluorol). Further, a volatile organic solvent for promoting rapid hardening after the application of the paste to the back surface of the tantalum wafer may be further included in the organic vehicle. These solvents and other solvents can be formulated in a variety of combinations to achieve the desired viscosity and volatility requirements. The organic solvent content in the aluminum paste of the present invention may be in the range of 5 to 25 wt% based on the total aluminum paste composition, or in a certain embodiment, at 1 〇 143174.doc 11 201015589 to 20 wt. /. Within the scope. The (or other) organic polymer may be present in the organic vehicle in a proportion ranging from 〇 to 20 wt% based on the total aluminum paste composition, or in some embodiments, at 5 to 1% by weight. A ratio within the range is present in the organic vehicle. The paste of the present invention may include a heat resistant inorganic compound and/or a metal organic compound. The "heat resistant inorganic compound" means an inorganic compound capable of withstanding the heat conditions in the firing process. For example, they have a melting point higher than the temperature experienced during the firing process. Examples include inorganic oxides (e.g., amorphous cerium oxide). Examples of metal organic compounds include tin organic compounds and zinc organic compounds (for example, zinc neodecanoate and stannous 2-ethylhexanoate. The aluminum paste of the present invention may include one or more organic additives (for example, surfactant, thickening) Agent, rheology modifier and stability (4)). The (or) organic additive may be part of the organic vehicle. However, in the preparation of the paste, the organic additive may also be added separately. The organic additive may be present in the aluminum paste of the present invention in a total proportion of, for example, 〇 to 1% by weight based on the total aluminum paste composition. The organic carrier content in (4) of the present invention may depend on the application method of the paste and The type of organic vehicle used, and thus the amount may vary. Based on the total aluminum paste composition, in one embodiment, the amount may be from 20 to 45 wt/0' or in an embodiment. The content may be in the range of 22 to 35 wt%. The amount of 2 to 45 (iv) includes an organic solvent, a possible organic polymer, and possibly an organic additive. The inscription paste of the present invention is a viscous composition, which may The granules and the optional glaze composition of the 143I74.doc •12·201015589 (etc.) are mechanically mixed with the organic vehicle. In one embodiment, a dynamic hybrid manufacturing method can be used (one equivalent to the conventional Rolling dispersion technology); rolling or other mixing techniques may also be used. The inscription paste of the present invention may be used as it is or may be diluted by, for example, adding an additional organic solvent; therefore, all other components of the aluminum paste may be reduced. Percentage by weight.
本發明的鋁膏可以用於矽太陽能電池的鋁背面電極之製 造中，或個別用於矽太陽能電池之製造中。該製造可以透 過以下方式實施：將該等鋁膏施加至矽晶圓的背面，亦 即，其他背面金屬膏（例別是像背面銀或銀/鋁膏）所覆蓋或 未覆蓋的那些;^晶圓表面部分。該科晶圓可以包括單晶 矽或多晶矽。在某一實施例中，該等矽晶圓可以具有ι〇〇 至250 Cm2的面積，以及18〇至3〇〇 μιη的厚度。然而本發 明的鋁膏甚至可以成功地使用在較大和/或較薄矽晶圓(例 如，具有小於180 μιη(特別是在14〇 μιη至低於18〇 範圍 内)的厚度和/或在大於250至4〇〇咖2範圍内之面積的矽晶 圓）之背面上的鋁背面電極之生產中。 將該等銘膏施加成為具有例如15至6〇叫之乾膜厚度。 通常，將它們施加成為-單層於料^圓时面上。銘 膏的施加方法可以為印刷（例如，謂片印刷（siii_e _ printing))，$在某—實施例中，_版印刷。本發明的銘 膏的施加黏度為Pa.s，所述黏度係採肢。OW 脈黏度計和14號心軸，透過—實用杯狀物⑽lity cup)在 143174.doc 13- 201015589 10 rpm轴轉速以及25°C條件下所測得。 在將該等銘膏施加於該等矽晶圓的背面後，可以使該等 晶圓達到一在100至300t範圍内的峰值溫度，以對它們進 行乾化有例如1至1 〇〇分鐘的時間。可使用以下設備進行乾 化，例如，帶式乾燥機、旋轉式乾燥機或固定式乾燥機7 特別是IR(紅外線）帶式乾燥機。 在施加銘膏之後，或在某—實施例中，在施加並乾化紹 膏之後，對本發明的銘膏進行燒製，以形成銘背面電極。 例如’可以使該等碎晶圓達到—在则至列代範圍内的峰 值溫度，以實施燒製有⑴分鐘的時間。例如，可採用單 段帶式爐或多段帶式爐（特別是多段ir帶式爐）來實 製。燒製係在氧氣存在的情況下（特別是在空氣存^ =下谜行。在燒製期間，可以移除（亦即，燃燒移除和^ =二特別是燃燒移除)有機物質(包括非揮 料 =在可能的乾化㈣h被蒸發的有機部分）。在燒^ 物質包括有機溶劑、可能的有機聚合物和 的有機添加齊卜在該等鋁膏包括玻璃料的 燒製期間可以發生另一個 中， 以將焯製實m 固製帛’亦即，玻璃料的燒結。可The aluminum paste of the present invention can be used in the manufacture of aluminum back electrodes for tantalum solar cells, or in the manufacture of tantalum solar cells. The fabrication can be carried out by applying the aluminum paste to the back side of the germanium wafer, that is, other back metal pastes (eg, like back silver or silver/aluminum paste) or those not covered; The surface portion of the wafer. The wafer may include single crystal germanium or polycrystalline germanium. In one embodiment, the germanium wafer may have an area of from 1 to 250 Cm2 and a thickness of from 18 to 3 μm. However, the aluminum paste of the present invention can even be successfully used on larger and/or thinner tantalum wafers (e.g., having a thickness of less than 180 μm (especially in the range of 14 μm to less than 18 μm) and/or greater than The production of aluminum back electrodes on the back side of the wafers of 250 to 4 〇〇 coffee area 2). These pastes are applied to have a dry film thickness of, for example, 15 to 6 bark. Usually, they are applied as a single layer on the surface of the material. The application method of the paste may be printing (for example, siii_e _ printing), and in some embodiments, _ printing. The applied paste of the present invention has an applied viscosity of Pa.s, and the viscosity is a limb. The OW pulse viscometer and the No. 14 mandrel were measured through a practical cup (10) lity cup at 143174.doc 13-201015589 10 rpm shaft speed and 25 °C. After the pastes are applied to the back side of the germanium wafers, the wafers can be brought to a peak temperature in the range of 100 to 300 tons to dry them for, for example, 1 to 1 minute. time. It can be dried using the following equipment, for example, a belt dryer, a rotary dryer or a stationary dryer 7 in particular an IR (infrared) belt dryer. After application of the paste, or in an embodiment, the paste of the present invention is fired after application and drying of the paste to form the front electrode. For example, the shredded wafers can be brought to a peak temperature in the range of up to the array to perform firing for a period of (1) minutes. For example, a single-stage belt furnace or a multi-stage belt furnace (especially a multi-stage ir belt furnace) can be used. The firing system is in the presence of oxygen (especially in the air memory). During the firing process, organic matter can be removed (ie, combustion removed and ^ = two, especially combustion removed). Non-wing = the organic part that is evaporated in the possible drying (four) h). The burning of the substance including the organic solvent, the possible organic polymer and the organic addition may occur during the firing of the aluminum paste including the frit. In the other, the solidification of the crucible is performed, that is, the sintering of the frit.
以將燒製實施成為所謂的T 金屬膏(亦即，用以厂“ /曰曰圓上所已施加之另外 面和/或背面電極所施期間㈣晶圓之表面上形成正 的共燒。-實金屬膏)-起進行 膏。 &正面銀膏和背面銀或背面銀/鋁 接下來 參考圖2來說明 一非限定範例 其中使用本發 143 Ϊ 74.doc 201015589 明的鋁膏製備一矽太陽能電池。 首先，製備一矽晶圓基底102。在該矽晶圓的受光面（正 面表面’通常p_n接面靠近該表面）上安裝正面電極（例如， 主要由銀組成的電極）104(圖2A)。在該矽晶圓的背面上， 塗抹銀或銀/鋁導電膏（例如，PV202或PV5〇2或PV583或 PV581 ’ 可在市場上從 E ! Du ρ_ 心 Nem〇urs andThe firing is carried out as a so-called T metal paste (i.e., on the surface of the wafer applied during the application of the other side and/or the back electrode applied to the wafer). - solid metal paste) - from the paste. & front silver paste and back silver or back silver / aluminum Next, a non-limiting example is described with reference to Figure 2, which uses the aluminum paste prepared by the present invention 143 Ϊ 74.doc 201015589矽 Solar cell. First, a wafer substrate 102 is prepared. A front surface electrode (for example, an electrode mainly composed of silver) 104 is mounted on the light receiving surface of the silicon wafer (the front surface 'usually the p_n junction is close to the surface). Figure 2A). On the back side of the germanium wafer, apply silver or silver/aluminum conductive paste (for example, PV202 or PV5〇2 or PV583 or PV581' available on the market from E! Du ρ_心Nem〇urs and
Company購得），以形成匯流條或垂片，進而能與其他成並 ❹ 聯電配置的太陽能電池組互連。在該矽晶圓的背面上，藉 由使用能與上述銀或銀/鋁膏等稍微重疊之圖案的網版印 刷，塗抹用以作為一太陽能電池的一背面（或p型接點）電極 的本發明之新型鋁膏106，然後，對該新型鋁奮1〇6進行乾 化（圖2B)。例如，在一IR帶式乾燥機中，使該晶圓達到 1〇〇至3〇o°c的峰值溫度，以對該等膏實施乾化有1至1〇分 鐘的時間。又，該鋁膏可以具有15至6〇 μπι的乾膜厚度， 以及該銀或銀/鋁膏的厚度可以是15至3〇 μιη。並且，該鋁 φ 膏與該銀或銀/鋁膏的重疊部分可以是約0.5至2.5 mm。 接著，例如在一帶式爐中，使該晶圓達到7〇〇至9〇〇艺的 峰值溫度， 以對該所獲得之基底進行燒製有丨至5分鐘的時 間，以便獲得該期望矽太陽能電池（圖2D)e以該鋁膏形成 現製’以除去該有機物 則同時燒結該玻璃料。 一電極110，其中已對該鋁膏進行燒製， 質’以及如果該銘膏包括玻璃料，則同畴 使用本發明的鋁膏所獲得之矽太陽能電池（如圖2D所示Company purchased) to form bus bars or tabs that can be interconnected with other solar cells in a parallel configuration. On the back side of the germanium wafer, a backside (or p-type contact) electrode for use as a solar cell is applied by screen printing using a pattern slightly overlapping with the silver or silver/aluminum paste or the like. The novel aluminum paste 106 of the present invention is then dried (Fig. 2B). For example, in an IR belt dryer, the wafer is brought to a peak temperature of 1 Torr to 3 〇 °C to dry the paste for 1 to 1 minute. Further, the aluminum paste may have a dry film thickness of 15 to 6 μm, and the silver or silver/aluminum paste may have a thickness of 15 to 3 μm. Also, the overlapping portion of the aluminum φ paste and the silver or silver/aluminum paste may be about 0.5 to 2.5 mm. Then, for example, in a belt furnace, the wafer is brought to a peak temperature of 7 〇〇 to 9 , to burn the obtained substrate for 5 minutes to obtain the desired 矽 solar energy. The battery (Fig. 2D) e is formed from the aluminum paste to remove the organic material while sintering the glass frit. An electrode 110 in which the aluminum paste has been fired, and if the paste comprises a glass frit, the same solar cell obtained by using the aluminum paste of the present invention is used (as shown in Fig. 2D).
在該破基底102的受光面（矣而、μ曰士 ％ h 上 143174.doc 15 201015589 成的銀或銀/鋁電極112(透過燒製銀或銀/鋁膏108所形 成）。 範例 (1)太味能電池的製造 太陽能電池之形成如下： ⑴在正面具有20 μιη厚的銀電極（PV145銀組成物，可在市 場上從Ε. I. Du Pont de Nemours and Company購得）的石夕基 底（面積243 cm2及p型（硼）塊狀矽的160 μιη厚多晶矽晶圓， 其具有一η型擴散POCl3發射器，表面以酸來進行組織化， 透過CVD在該矽晶圓的發射器上施加SiNx抗反射塗層 (ARC))的背面上印刷一銀/鋁膏（PV202，一可在市場上從 Ε. I. Du Pont de Nemours and Company購得之銀/紹組成 物），並將其乾化成5 mm寬的匯流條。接著，以一30 μιη乾 膜厚度網版印刷一用於太陽能電池的背面電極的鋁膏，以 在兩邊緣處提供該鋁膜與該銀/鋁匯流條有1 mm之重疊， 以確保電性連接。在燒結前，乾化該網版印刷鋁膏。 該實例鋁膏包括72.5 wt%的鋁粉（每一情況的平均粒度 為6 μιη)及27.5 wt%的聚合樹脂和有機溶劑所組成的有機 載體。對照膏A中的鋁粉完全由空氣霧化的（結狀）粉末所 構成。膏B至膏E(根據本發明）中的鋁粉包括空氣和氮氣霧 化的（結狀和球狀）粉末之混合物，其中球狀粉末的含量為 10至90 wt%。對照膏F中的鋁粉完全由氮氣霧化的（球狀） 粉末所構成。 (ii)然後，在Centrotherm爐中以數個區域溫度（該等區域溫 143174.doc •16- 201015589 度被界定成為：區域1=450°C、區域2=520°C、區域3 = 57〇°C及最後區域=95〇°C )在3000 mm/min帶速下燒製該等 印刷矽晶圓，從而該等晶圓達到850°C的峰值溫度。在燒 製後’該等金屬化晶圓變成功能性光電元件。 進行電氣性能和赵曲的測量。 (2)測試程序 效率 將根據上述方法所製成的太陽能電池置於一商用測 試器（由EETS Ltd.所提供）中，以便測量光轉換效率。在該 I-V測試器中的燈泡模擬已知強度（大約1000 W/m2)的太陽 光並照射該電池的發射器。隨後’以4個電探針接觸在該 等被燒製電池上的敷金屬。透過電阻之調整來測量該等太 陽能電池所產生的光電流（Voc，開路電壓；Isc，短路電 流）’以便計算I-V響應曲線。隨後，從該；[_v響應曲線可推 算出填充因子（FF)和效率（Eff)值。 麵曲的測量 將翹曲（電池彎曲）定義為：當在一平坦表面上進行測量 時，該被燒製電池的中心在室溫下的最大撓曲高度。翹曲 測量透過以下方法進行：將該等電池放在一金屬平坦基座 上，並且使用一具有微米解析度的度盤規（dW胖扣弘）， 以測量每一電地的最大撓曲，亦即，測定該晶圓中心離該 平坦基座表面的距離。 表!中所引用㈣例A至F描述該等銘膏的電氣特性和魅 曲特性成為該球狀鋁粉的含量之函數。表丨中的數據證 143174.doc 17 201015589 實，相對於使用對照膏A和F所製成的太陽能電池，使用根 據範例B至E的鋁膏所製成的太陽能電池顯示出在電氣性能 與該等電池之翹曲間具有更好的平衡。 表1 範例 球狀鋁粉含量 (wt%) Voc (mV) Isc (A) Eff(°/〇) FF (%) 勉曲 (μιη) A 0 591.9 8.83 15.45 71.69 1902 B 30 597.1 8.89 15.88 72.53 2026 C 50 598.0 8.86 15.82 72.86 1703 D 70 600.2 8.98 15.99 72.27 1651 E 90 600.4 8.97 16.14 72.96 1659 F 100 599.9 8.79 15.73 72.63 1707 【圖式簡單說明】 圖1A至1F係描述一矽太陽能電池之示範製造的製程流 程圖。 圖1所示的元件符號之說明如下。 10 : p型矽晶圓 20 : η型擴散層 30 :抗反射塗層，例如SiNx、TiOx、SiOx 40 : p+層（背面電場，BSF) 60 :背面上所形成的鋁膏 61 :鋁背面電極（透過燒製背面鋁膏所獲得） 70:背面上所形成的銀或銀/鋁膏 71 :銀或銀/鋁背面電極（透過燒製背面銀或銀/鋁膏所獲 得） 143174.doc • 18 · 201015589 500:正面上所形成的銀膏 501 :銀上電極（透過燒製正面銀膏所獲得） 圖2A至2D說明用以使用本發明的導電鋁膏製造—矽太 陽能電池的製造方法。圖2所示的元件符號的說明如下。 102矽基底（矽晶圓）On the light-receiving surface of the broken substrate 102, silver or silver/aluminum electrode 112 (formed by firing silver or silver/aluminum paste 108) formed on 143174.doc 15 201015589. The manufacture of solar cells is as follows: (1) A silver electrode with a thickness of 20 μm thick on the front side (PV145 silver composition, commercially available from Ε. I. Du Pont de Nemours and Company) A 160 μm thick polycrystalline germanium wafer having a base (area of 243 cm2 and p-type (boron) bulk) having an n-type diffused POCl3 emitter, the surface being organized with acid, and the emitter of the germanium wafer being CVD A silver/aluminum paste (PV202, a silver/sauerium commercially available from Ε. I. Du Pont de Nemours and Company) is printed on the back side of the SiNx anti-reflective coating (ARC). It was dried into a 5 mm wide bus bar. Next, an aluminum paste for the back electrode of the solar cell was screen printed at a dry film thickness of 30 μm to provide the aluminum film and the silver/aluminum confluence at both edges. Strips have an overlap of 1 mm to ensure electrical connection. Dry the web before sintering Printing aluminum paste. The aluminum paste of this example comprises 72.5 wt% aluminum powder (average particle size of 6 μιη in each case) and 27.5 wt% of an organic vehicle composed of a polymer resin and an organic solvent. The aluminum powder in the control paste A is completely It consists of an air atomized (junction) powder. The aluminum powder in paste B to paste E (according to the invention) comprises a mixture of air and nitrogen atomized (junctional and spherical) powders, of which spherical powder The content is from 10 to 90% by weight. The aluminum powder in the control paste F is completely composed of a nitrogen atomized (spherical) powder. (ii) Then, in the Centrotherm furnace, several regional temperatures (the temperature of the regions 143,174. Doc •16- 201015589 degrees are defined as: zone 1 = 450 ° C, zone 2 = 520 ° C, zone 3 = 57 ° ° C and final zone = 95 ° ° C) firing at 3000 mm / min belt speed The wafers are printed so that the wafers reach a peak temperature of 850 ° C. After firing, the metallized wafers become functional photovoltaic elements. Electrical performance and measurement of Zhao Qu. (2) Testing Program efficiency The solar cell fabricated according to the above method is placed in a commercial tester (by EETS L Td. provided) to measure the light conversion efficiency. The bulb in the IV tester simulates a known intensity (approximately 1000 W/m2) of sunlight and illuminates the emitter of the battery. Then 'four electric probes The needle contacts the metallization on the fired cells. The photocurrent (Voc, open circuit voltage; Isc, short circuit current) generated by the solar cells is measured by adjusting the resistance to calculate the IV response curve. Then, from this; [_v response curve can be derived from the fill factor (FF) and efficiency (Eff) values. Measurement of the curvature of curvature The warpage (battery bending) is defined as the maximum deflection height of the center of the fired battery at room temperature when measured on a flat surface. The warpage measurement is performed by placing the cells on a flat metal base and using a micrometer resolution dial gauge to measure the maximum deflection of each electrical field. That is, the distance from the center of the wafer to the surface of the flat substrate is measured. References in Table! (4) Examples A to F describe the electrical characteristics and enchantment characteristics of these pastes as a function of the content of the spherical aluminum powder. The data in the form 143174.doc 17 201015589 In fact, compared to the solar cells made using the control pastes A and F, the solar cells made using the aluminum pastes according to the examples B to E showed electrical properties and There is a better balance between the warpage of the battery. Table 1 Example Spherical aluminum powder content (wt%) Voc (mV) Isc (A) Eff (°/〇) FF (%) 勉曲(μιη) A 0 591.9 8.83 15.45 71.69 1902 B 30 597.1 8.89 15.88 72.53 2026 C 50 598.0 8.86 15.82 72.86 1703 D 70 600.2 8.98 15.99 72.27 1651 E 90 600.4 8.97 16.14 72.96 1659 F 100 599.9 8.79 15.73 72.63 1707 [Simplified illustration of the drawings] Figures 1A to 1F depict a process flow diagram for the demonstration manufacturing of a solar cell. . The description of the component symbols shown in Fig. 1 is as follows. 10: p-type germanium wafer 20: n-type diffusion layer 30: anti-reflection coating, for example, SiNx, TiOx, SiOx 40: p+ layer (back surface electric field, BSF) 60: aluminum paste 61 formed on the back surface: aluminum back electrode (obtained by firing the back aluminum paste) 70: Silver or silver/aluminum paste 71 formed on the back side: silver or silver/aluminum back electrode (obtained by firing the back silver or silver/aluminum paste) 143174.doc • 18 · 201015589 500: Silver paste 501 formed on the front side: silver upper electrode (obtained by firing the front silver paste) FIGS. 2A to 2D illustrate a method of manufacturing a solar cell using the conductive aluminum paste of the present invention. The description of the component symbols shown in Fig. 2 is as follows. 102矽 substrate (矽 wafer)
104受光表面側電極 106第一電極的膏組成物 108第二電極的導電膏 110第一電極 112第二電極 【主要元件符號說明】 10 P型矽晶圓 20 η型擴散層 30 抗反射塗層，例如SiNx、TiOx、SiOx 40 P+層（背面電場，BSF) 60 背面上所形成的鋁膏 61 铭背面電極（透過燒製背面鋁膏所獲得） 70 为面上所形成的銀或銀/鋁膏 71 銀或銀/鋁背面電極（透過燒製背面銀或 銀/鋁膏所獲得） 102 矽基底（矽晶圓） 104 受光表面侧電極 106 第一電極的膏組成物 108 第一電極的導電膏 143174.doc -19· 201015589 110 112 500 501 第一電極 第二電極 正面上所形成的銀膏 銀上電極（透過燒製正面銀膏所獲得） 143174.doc -20-104 light-receiving surface side electrode 106 first electrode paste composition 108 second electrode conductive paste 110 first electrode 112 second electrode [main element symbol description] 10 P-type germanium wafer 20 n-type diffusion layer 30 anti-reflective coating For example, SiNx, TiOx, SiOx 40 P+ layer (back surface electric field, BSF) 60 Aluminum paste formed on the back surface 61 Front back electrode (obtained by firing the back aluminum paste) 70 Silver or silver/aluminum formed on the surface Paste 71 Silver or silver/aluminum back electrode (obtained by firing back silver or silver/aluminum paste) 102 矽 substrate (矽 wafer) 104 Light-receiving surface side electrode 106 Paste composition of the first electrode 108 Conductivity of the first electrode Paste 143174.doc -19· 201015589 110 112 500 501 Silver paste silver upper electrode formed on the front side of the second electrode of the first electrode (obtained by firing the front silver paste) 143174.doc -20-